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Abstract

It is well known that death of the tops of practically all prairie grasses occurs each fall in temperate grasslands where the soil is regularly frozen. Year after year new shoots replace the old ones in this vegetation of long- lived perennials. But as to what portion of the root system is retained and over what period of time, we are almost without information. This maintains despite the fact that much work has been done to increase our knowledge of the root systems of prairie grasses. Since the early studies of Weaver (6, 7) on their depth and lateral extent, detailed investigations have been made by Pavlychenko (1) upon their rate of growth, total root length, and quantity and quality of root material. The quantity of root material under different grassland climates has been ascertained by Shtvely and Weaver (2), and the quantity under different degrees of utilization of these grasses in the same climate by Weaver and Harmon (8). Weaver, Hougen, and Weldon (9) studied the amount of root material at different soil depths; but the length of life of the roots of prairie grasses, except for brief study by Stoddart (4), seems to have been entirely neglected. However, an investigation on the longevity of the seminal roots of certain grasses has recently been made by Weaver and Zink (10).